1. Field of the Invention
This invention relates to a novel prescription lens, mainly suited for ophthalmic applications, which can be formed to almost any shape and any thickness the designer wishes to, and a method which the design is synthesized from its specification.
2. Terms Definition
The term xe2x80x9ceyewearxe2x80x9d as used herein is defined as any light-transmitting element or elements in front of the eyes.
The term xe2x80x9cprescriptionxe2x80x9d as used herein is defined as a specific combination of optical parameters that meets the needs of a particular person in purpose to solve a large variety of treatments and diagnostic problems known to eye specialists, or the required optical function/properties whenever the article is not an ophthalmic lens. The term xe2x80x9cdiffractive surfacexe2x80x9d as used herein is defined as an optical surface having all over the surface plurality of edges or apertures or protrusions that are designed and made in accordance with the Interference phenomena. Only whenever the exact spatial locations (in resolution of few wavelengths) of said edges or apertures or protrusions have an indispensable influence on the image quality, the surface is defined as a diffractive surface.
The term xe2x80x9cdiscontinuous surfacexe2x80x9d as used herein is defined as a surface having plurality of points and/or curves wherein the first derivative is not continuous.
The term xe2x80x9csaw-toothed surfacexe2x80x9d as used herein is defined as a surface having plurality of discontinuities. That surface may looks like a saw-toothed surface and/or having a steps function nature and/or having plurality of grooves or protrusions or saw-teeth and/or may be defined as a surface that contains plurality of points wherein the surface not being continuously differentiable, and herein all these terms are equivalent.
The term xe2x80x9cThieberger-design-lensxe2x80x9d as used herein is defined as the novel thin lens of this invention, in purpose to distinguish it from the previous art lenses.
3. Description of the Prior Art
When a well eyesight person wants to use any eyewear, he is limited only by the industry wide availability of eyewear shapes and materials. When a person suffers from visual impairment wants to use any eyewear, not only he is limited by the industry wide availability of eyewear shapes and materials but he is limited also by the industry availability of prescription eyewear, which has limited shapes and materials available.
Until now, a method, having very good results, that converts any unprescription eyewear to a prescription one was not available. As a result, people suffer from visual impairment had to use prescription glasses or a combination of thick prescription lenses and a big eyewear instead of using any eyewear they want. The wish has been expressed to have a very thin and lightweight lens, with very good optical quality, that by adhering to the inside or outside surface of the eyewear, will convert an unprescription eyewear to a prescription one.
Unprescription eyewear designers are free to design their eyewear to any shape and thickness they want, therefore, we have plenty of fashion and/or user-friendly eyewears, such as, but not limited to, sunglasses, goggles, sport glasses, swimming glasses, diving masks, shooting glasses, helmets, gas masks, etc. On the contrary, prescription eyewear designers are seriously limited by the shape and thickness of prescription lenses, therefore, their creativity is restricted and not exploited appropriately.
Until now, a method, having very good results, that enable to form a prescription lens in any shape and almost any thickness the designer wants was not available. As a result, people who suffer from visual impairment have a small amount of shapes to choose from.
The wish has been expressed to have a prescription lens which is very thin, lightweight, not fragile, can have any desired shape, and have very good optical quality. The previous art prescription lenses are rigid and thick. Shaping and cutting those lenses require expensive tools which are not accessible to most of the people. As a result, most of the people don""t have unique eyewears. People cannot cut their lenses to the shape they want, fashioners cannot cut the lenses to shapes that will fit to the dress, the haircut, the car. they designed, etceteras, herein after refer to xe2x80x9crecreational stuffxe2x80x9d.
The industry does not consider it practical to prefabricate a stock of lenses having every possible power of each parameter in every possible combination that may be needed. Consequently, a sizable proportion of eyeglass lenses are custom made at the facilities of dispensing opticians or optical laboratories.
Lenses have traditionally been formed as a single integral body of glass or plastic. Grinding or molding such lenses to meet the specifications of a particular prescription requires costly equipment, highly skilled technicians and is time consuming. In addition, the lens is thick and available in very small amount of shapes. It has been found that the fabrication of prescription lenses can be economically accomplished in a more rapid manner with a laminated lens construction in which two or more lens layers/wafers are bonded together with a transparent adhesive.
The laminate construction enables assembly of lenses having any of a large number of different combinations of optical parameters from a relatively small stock of prefabricated lens layers of different configurations. Combinations of the layers can, for instance, provide lenses having any of a large number of different powers as the power of the lens is the summation of the powers of the layers. Cylinder correction for astigmatism can be adjusted by an appropriate rotation of one layer relative to the other prior to bonding of the layers. Bifocal or multifocal layers can be used when called for by the prescription and interlayer of light absorptive, light reflective or polarizing material can easily be provided between the layers.
The fabrication of laminated lenses is subject to certain problems which have not heretofore been adequately addressed and resolved. The final laminated lens is thick. The layers are available in a very limited amount of shapes and are not designed to bond to an eyewear that has surface that is not spherical or toric. In addition, The laminated lenses are usually frailer than regular lenses and elastic laminated lenses are not available.
In 1748, Count Buffon proposed to grind out of a solid piece of glass a lens in steps or concentric zones, in order to reduce the thickness of the lens to a minimum. In 1822, Augustin Fresnel, for whom the Fresnel lens is named, constructed a lens in which the centers of curvature of the different rings receded from the axis according to their distances from the center.
Modem Fresnel lenses consist of a series of concentric prismatic grooves, designed to cooperatively direct incident light rays to a common focus or focuses. This type of lens is thin, lightweight, can be made elastic, shook resistance, almost unbreakable, and can be accurately and cheaply mass-produced using replication techniques. The problem with Modem Fresnel lenses is that they are limited to flat or rotationally symmetric surfaces. As a result, when a designer design an eyewear which contains Fresnel lens, one of his considerations must be the lens shape.
U.S. Pat. Nos. 3,698,854 and 3,904,281, each issued to Jampolsky, disclose a thin, fully conformable, planarly smooth, plastic membrane which applied and made to adhere with finger pressure to a conventional spectacle lens. The step quickly changes one or more optical characteristics of the spectacle lens or provides a change in the light transmission across the field of view. Those patents force a planarly smooth thin Fresnel lens to adhere to any light transmitting element, although the Fresnel lens and the light transmitting element have initially non-matching surfaces. As a result, there were optical imperfections and distortions and aberrations visible to the wearer. The planarly smooth Fresnel lens does not readily adhere to curved surfaces on a permanently basis and was susceptible to trapping bubbles between a base surface and itself.
U.S. Pat. No. 4,950,057 issued to Shirayanagi, disclose progressive multi-focal ophthalmic lens having a front refractive surface and a rear refractive surface one of which is a progressive surface whose refractive power changes continuously with the other being a non-progressive surface. The progressive surface is formed as a Fresnel lens surface composed of microscopic steps so that the macroscopic shape of the progressive surface generally conforms to that of the non-progressive surface.
The shapes of the lenses according to U.S. Pat. No. 4,950,057 are limited to spherical and toric surfaces, as Shirayanagi states in the patent xe2x80x9cIt is also possible to render the non-progressive surface toric rather than sphericalxe2x80x9d.
The object of U.S. Pat. No. 4,950,057 is to provide a thinner multi-focal ophthalmic lens. Shirayanagi do not disclose how to produce a prescription lens that can have any desired shape and/or synthesis from its specifications, do not disclose laminated lenses, do not disclose elastic lenses, do not disclose lenses which are too thin to provide a desirable degree of impact strength, do not disclose lenses that adhere to an eyewear, do not disclose lenses which can be cut using simple cutting accessories, do not disclose protected lenses, and do not disclose a method that controls on the viewed geometric pattern made by the Fresnel lens.
Another approach to producing thin and lightweight prescription lenses involves the use of diffractive optics. Few of the shortcomings of diffractive optics lenses are that they can imitate only a multi-focal lens. A diffractive lens must be designed for light of a particular wavelength and will work most efficiently for light at that wavelength. Only about 40% of the light incident on the lens is used for near vision with another 40% being used for far vision. The remaining 20% is not used for either near or far vision, but rather is lost to higher orders of diffraction. This represents the best theoretical case and in manufacturing reality even less light is available due to manufacturing difficulties. Difficulty of manufacture represents another shortcoming of diffractive lenses since the diffractive surface must be in tolerance on the order of the wavelength of light.
U.S. Pat. No. 4,210,391 issued to Cohen, disclose multi-focal diffractive zone plate, methods for manufacture it, and methods for protecting the saw-toothed surface. That lens has limited number of different shapes, as Cohen states in the patent xe2x80x9cThe carrier lens or body of course, is constructed according to the usual principles governing the design of an optical lens with the surfaces S1 and S2 either spherical, sphero-cylindrical, or of any other appropriate lens design.xe2x80x9d
U.S. Pat. No. 4,960,326 issued to Dauvergne, disclose a lenticular lens for eyewear which is being formed with a curved substrate having a plurality of imprinted miniature lenses. Dauvergne assumes that the user""s mind ignores the web-like interface between the lenses when a user peers through a lens complex positioned close to the eye. But the result is poor, as Dauvergne states in the patent xe2x80x9cThe proposed eyewear is not considered a substitute for prescription lenses, but is an auxiliary item that is preferably tinted and styled to provide an attractive appearance.xe2x80x9d
Previous attempts to synthesize a lens from its specifications can be seen, for example, in U.S. Pat. Nos. 4,613,217 and 4,676,610 and 4,787,733. The main problem with those patents is that the final prescription lenses are smooth, i.e., no surface jump discontinuities and no discontinuous changes in the surface slope. As a result, those lenses are thick and can have a very limited amount of shapes because of the connection between the macroscopic shape of the optical article to its optical characteristics
U.S. Pat. No. 5,299,062 issued to Ogata, disclose a lens consists of a glass lens having an organic corrective layer consisting of a blazed grating of annuli whose angles are formed to correct aberrations in the glass lens. In addition, Ogata disclose a method of manufacturing the lens in which the resin corrective layer is molded to the glass lens. According to that patent, the organic layer is limited to the purpose of correcting the aberrations of the glass lens.
The problem of the connection between the macroscopic shape of the optical article to its optical characteristics strikes mirror designers too. Mirror designers are seriously limited by the shape of the mirror, therefore, their creativity is restricted and not exploited appropriately. For instance, vehicle manufacturers spend huge percents of their development budgets on impressive designs, but concerning to mirrors, all of them are forced to use the same flat mirror.
Prior art unifocal and multifocal Fresnel mirrors are limited to flat or rotationally symmetric surfaces. Prior art mirrors construct of plenty of microscopic spherical lenses suffers from blurred image.
In view of the aforementioned needs and problems in the prior art, it is a primary object of the present invention to provide an optical surface and more specifically a prescription optical surface, such as an optical device and ophthalmic lens. Novel mirrors are also considered a part of this invention. These products are commonly referred to as Thieberger design lenses and mirrors that can have almost any desired shape and thickness. There is almost no connection between the thickness and the macroscopic shape of Thieberger-design-lens to its optical characteristics. Therefore, It is another object of the present invention to provide a method which the design is synthesized from its specification. The design method permits generation of different families of lenses, embodying different selections of other parameters such as zones size and placement, eye path, etc.
Thieberger-design-lens has three main preferred embodiments. An Add-on type Thieberger-design-lens, a Stand-alone type Thieberger-design-lens, and a composition of the former.
Add-on type Thieberger-design-lens is bonded or attached to an eyewear. Its main purpose is to convert an unprescription eyewear to a prescription eyewear or to change one or more optical characteristics of any prescription or unprescription optical element, what ever its kind or use.
It has been discovered that if we want the Add-on type to be very thin, have very good optical qualities and acceptable bond, the lens"" surface and the eyewear""s surface have to be initially matching. As the Add-on type will initially fit to the eyewear""s surface more closely, it will have less aberrations, will be thinner, will bond better and will be less visible to the wearer and observers.
Add-on Thieberger-design-lens by itself may also be too thin to provide a desirable degree of impact strength, thus cannot be used individually.
The Add-on Thieberger-design-lens may cover all the eyewear""s lens surface or only a part of it. It may be attached or adhere permanently or impermanently to the front and/or rear surface of the eyewear. It may be used for cost reduction.
The main purpose of the Stand-alone type Thieberger-design-lens is to provide a better alternative to conventional prescription lenses.
It is another object of the present invention to provide a prescription lens which may be very light-weight, elastic (suitable for instance to sport activities, safety glasses, children""s glasses, etc.), almost unbreakable, cheaply mass-produced, with large angular viewing range, with high power and very low aberrations, enough thin and soft to enable people to cut and shape their lenses as they wish by using simple cutting accessories such as scissors and the like.
It is another object of the present invention to provide a laminated Thieberger-design-lens made of two or more layers. Light reflective or polarizing material may be provided between the layers. One of the layers can be provided with photochromic characteristics. That laminated lens has all the economic advantages of the previous art laminated lenses and in addition, has all the advantages of Thieberger-design-lens.
Plastic lenses are less fragile, lighter, and more economically mass-manufactured then glass lenses, but are inferior to glass lenses with respect to hardness, scratch resistance, resistance to radiation, ability to receive a wide range of lasting surface treatments (such as anti-reflecting, reflecting, coloration), and photochromic durability.
It is another object of the present invention to provide a high quality laminated composite lens, composed of one or more organic Thieberger-design-layer and a glass layer (that can have any shape of course). This composite lens incorporates all the advantages of organic lenses and all the advantages of glass lenses. In addition, it can have highly impact resistance and highly shatter resistance. The organic layer may also be used for correcting aberrations of the glass layer, such as, for example, chromatic aberration.
Because the photochromic lens or layer (which can be made of glass or plastic) of the present invention can have a uniform thickness, when it is exposed to sunlight it will assume a uniform darkness. That uniform thickness provides a significant optical advantage over conventional photochromic prescription lenses which have varying thickness that caused to non uniform darkness when exposed to sunlight.
Thieberger-design-lens may be combined with conventional stock lenses. Comparing to the known in the art laminated lenses, the result is thinner, lighter, and in some cases less fragile.
It is another object of the present invention to provide a thin, lightweight, and high quality prescription lenses for patients who have suffered cataract, or some retinal or optic nerve damage which results in decreased visual function due to decreased visual acuity, or decreased visual field, or formation of blind spots, or a combination of thereof. This object can be achieved since the prescription lens of the present invention has rough surface, which permit individual calculation of every normal to the prescription lens in such a way that optimal correction can be obtained for each eye viewing angle in the viewing zone, and/or optimal minimization of the residual/peripheral astigmatism/blur can be obtained for each viewing-axis depending on the selected eye model and according to the lens characteristics and profile of use.
Thieberger-design-lens may be partially or entirely tinted to pass or reflect certain wavelengths of light, may be diffused, or blurred uniformly or differentially, may have selective opaque or transmitting areas or a combination thereof, may be coated with polarizing material, may be coated with scratch resistant material, may be coated with holographic recording material as disclosed for example in U.S. Pat. No. 5,432,623, may be marked as disclosed for example in U.S. Pat. No. 4,619,504.
The prescription parameters (such as eye path location, axis, power, cylinder location, and etceteras) may be noted on the lens with impermanently ink or on a non-stick protective covering, etc.
In a preferred embodiment, Thieberger-design-lens is covered with a protective layer which protects against scratches, dust, etc.
It is a further object of the present invention to provide a method that controls on the lens"" viewed geometric pattern (caused be the discontinuities of the surface) in purpose to make a more aesthetic and fashioned article, and to enable the designer to optimize to minimum the diffraction aberrations and the image blur and to optimize the manufacturing process.
In order to carry out all the objects of the present invention, the macroscopic surfaces of the Thieberger-design-lens are first defined by the lens"" designer. One surface (or both of them) is not smooth but has a microscopic surface that looks like a saw-toothed surface, sometimes refer to as a saw-toothed zone or as a saw-toothed surface zone (each saw-tooth is smooth of course). The design process assumes that the locations of the object, the lens, and the required image are known. By using Ray-tracing technique we calculate the microscopic normals to the lens that will form the required image. The final microscopic surface (which looks like a saw-tooth surface) will be obtained by a continuously summation of the slopes (which are obtained from the previous calculated normals). Before starting to sum the slopes, we set a set of conditions, which will be called herein xe2x80x9cGeometric pattern conditionsxe2x80x9d or predetermine condition/s. Those conditions can be any one or all of the following: condition on H, geometric condition, diffraction consideration, quality of the formed image, cosmetic factors, grinding technique, manufacturing technique, surface durability, tolerance budgeting methods. These conditions, finally, determine the size and height of each saw-tooth, i.e., until when the slope summation process will continue and when there will be a discontinuity and a new slope summation for a new saw-tooth will begin. The Geometric Pattern Conditions can determine directly the size or height of the saw-tooth by using a condition on the shape or on the height, or determine indirectly by using a condition on the diffraction effect or the image quality, i.e. the slope summation process will continue until the diffraction effect will get to a some predetermined value or the image blur be less than a predetermined value.
It is another object of the present invention to provide unifocal and multifocal mirrors which can have any desired shape and can be made flexible.
All the noted previous art problems are solved by the novel prescription lens of the present invention, which can have any desired shape and almost any thickness.